The present invention relates to a display rack used in holding a carrying board for holding articles for display, and more particularly to such a display rack which enables the carrying board to be smoothly adjusted to the desired elevation.
There is known a display rack comprised of an upright support, the upright support having a plurality of longitudinal sliding grooves equiangularly spaced around the periphery, a sliding block moved along one longitudinal sliding groove of the upright support, the sliding block having a vertical locating groove at a front side thereof the two through holes aligned at two opposite sides of the vertical locating groove, a screw rod inserted through the through holes on the sliding block, the screw rod having a left-handed thread at one end and a right-handed thread at an opposite end, two clamping blocks respectively mounted on the screw rod at two opposite ends, the clamping blocks each having a coupling block inserted into one longitudinal sliding groove at the upright support and a clamping base adapted to clamp the sliding block, the clamping base of one of the clamping blocks having a left-handed screw hole threaded onto the left-handed thread of the screw rod, the clamping base of the other of the clamping blocks having a right-handed screw hole threaded on the right-handed thread of said screw rod, and a holder frame fixedly mounted on the screw rod on the middle within the locating groove at the sliding block, and adapted to hold a board for carrying things, the holder frame being turned between a first position where the screw rod is rotated in one direction to move the clamping blocks apart from the sliding block, enabling the sliding block to be moved along the corresponding longitudinal sliding groove to the desired elevation, and a second position where the screw rod is rotated in the reversed direction to move the clamping blocks towards each other, causing the clamping blocks to clamp on the sliding block and a part of the upright support, enabling the sliding block to be firmly retained to the upright support at the desired elevation. This structure of display rack is functional, however when the holder frame is turned to the non-operative position to release the sliding block, the board and the load on the board may fall with the sliding block to the ground, causing the displayed articles to be damaged. Therefore, when the user turns the holder frame to adjust the elevation of the sliding block with one hand, the user must hold the board with the other hand.
The present invention eliminates the aforesaid problem. According to the present invention, a pulley is suspended inside the upright support and aimed at a transverse through hole within the longitudinal sliding groove at the upright support, a spring member is fixedly mounted inside the upright support at the bottom, and a steel cable is inserted through the transverse through hole on the upright support and passed through the pulley and connected between the spring member and the sliding block to prevent the sliding block from falling down suddenly when the sliding block is release from the clamping blocks.